Tandem Plate for Friction Rock Stabilizer

ABSTRACT

A tandem plate for use with a friction rock stabilizer of the kind that includes an elongated metal tube driven into a bore drilled in a rock wall and having an end adapted to engage a bearing plate. The tandem plate includes a substantially planar metal sheet having an upper surface, a lower surface and an overall dimension which is larger than the size of the bearing plate. An opening adjacent the center allows the tube to pass therethrough. The lower surface engages the rock wall while the upper surface of the tandem plate engages the bearing plate. A tabs on the upper surface, formed by punching and bending parts of the planar sheet from which the tandem plate is made, engage the bearing plate while the tube is being driven into the bore. A plurality of ribs formed on the tandem plate increase the strength thereof.

BACKGROUND OF THE INVENTION

The present invention is directed toward an improved tandem plate foruse with friction rock stabilizers and, more particularly, toward atandem plate (sometimes referred to as a butterfly plate) that caneasily be attached to a bearing plate of a rock stabilizer when desiredso that a miner can handle the entire assembly with two hands.

Ground support, especially in the mining industry, is an importantsafety factor that must be taken into consideration during any type ofexcavating activity. Rock stabilizers, or rock bolts, have been used formany years to support exposed rock during mining operations. A number oftypes of rock bolts are used depending on the situation, such as groundconditions, costs, personal preferences, etc. There are three primarytypes of rock bolts. The first is an expansion shell type bolt where ascrew threaded steel bar is inserted into a drilled hole in the rock.The bolt has a “shell” at its tip. Once the bolt is inserted into thedrilled hole and is turned, the shell expands to the sides of the holeand grips the rock so that the steel bar can then be tensioned. Thisresults in bolting the rock strata layers together.

Grouted bar type stabilizers are also known. These include a ribbed barwhich is inserted into a drilled hole and which hole is then furtherfilled with a specialized cement or resin-based grout. This type ofsupport depends directly on the bond between the rock and the grout andthe grout and the steel bar and acts like a reinforcing bar.

Another effective anchoring system that is currently used is commonlyreferred to as a Split Set available from International Rollforms, ofDeptford, N.J. A Split Set is a brand of a friction rock stabilizer thatincludes an elongated tube and a bearing plate. The tube is typicallymade from resilient steel and has a slit along its length so that thetube will be compressed during insertion into a pre-drilled bore in amine roof or wall. One end of the tube is tapered and the other end hasa ring flange. In order to install the split set, the bearing plate isplaced over the end of the tube so as to engage the ring flange and thetapered end of the tube is then driven into the drilled hole in therock. As tube slides into place, the slot narrows, exerting radialpressure against the surface over its full contact length and providesplate load support. The result is a tight grip brought about by thefriction generated between the outer steel wall of the tube or cylinderand the inner side wall of the bore in the wall. Such systems aredescribed, for example, in U.S. Pat. No. 5,295,768 to Buchhorn et al.,U.S. Pat. No. 4,652,178 to Kates et al., U.S. Pat. No. 4,445,808 toArya, and U.S. Pat. No. 4,382,719 to Scott.

Bearing plates, such as mentioned above, can be use with substantiallyany of these rock bolts or friction rock stabilizers. The purpose of thebearing plate is to distribute the load applied by the stabilizeragainst the surface of the rock. That is, the bearing plate transfersthe weight load of the rock face to the bolt.

In some applications, an additional plate, commonly referred to as atandem plate is used in combination with a bearing plate. The tandemplate placed on the bearing plate and the bolt is then threaded throughthe two plates. The tandem plate is larger in size than the bearingplate and is usually made of a much lower gauge steel material so thatit can conform to some degree to the rock face of the mine roofsurrounding the bolt. The primary purpose of the tandem plate is toinhibit fretting of the rock face about the bolt. That is, the tandemplate supports loose material or rocks and prevents them from falling.

When utilizing a tandem plate in addition to the bearing plate, it isnormally just placed over the bolt along with the bearing plate and isallowed to simply move freely. This creates problems when the bolt isbeing driven into place as the plate may not line up properly. Inparticular, with prior art tandem plates, both plates are free to rotateas the bolt is hammered into the hole. The bearing plate should seatinto the square pocket in the tandem plate, but as the two plates canrotate freely, they may not seat properly as the bolt installation iscompleted, thereby crushing the tandem plate.

One solution to this problem is to weld the tandem plate to the bearingplate such as shown in U.S. Pat. No. 5,628,587 to Lesslie or tointerconnect a tandem plate and a bearing plate by crimping themtogether to essentially form a single plate such as shown in U.S. Pat.No. 5,791,828 to Fergusson. Such combinations, however, are notsatisfactory for several reasons. Most significantly, not all boltsrequire both a bearing plate and a tandem plate. Thus, workers wouldhave to carry both the combined plates such as taught by Lesslie orFergusson and bearing plates without the tandem plate attached.

There is, therefore, a need for a tandem plate for use with frictionrock stabilizers that can easily and quickly be applied to a bearingplate in the field if such is ever deemed to be necessary or beneficial.

SUMMARY OF THE INVENTION

The present invention is designed to overcome the deficiencies of theprior art discussed above. It is an object of this invention to providea new tandem plate for a friction rock stabilizer that has advantagesover prior art plates.

It is a further object of the present invention to provide a new tandemplate that is relatively simple to install.

It is a still further object of the present invention to provide a newtandem plate that can simply and quickly be applied to a bearing platein the field whenever desired.

In accordance with the illustrative embodiments demonstrating featuresand advantages of the present invention, there is provided a tandemplate for use with a friction rock stabilizer of the kind that includesan elongated metal tube adapted to be driven into a bore drilled in arock wall and a second end adapted to engage a bearing plate. The tandemplate is comprised of a substantially planar sheet of metal having anupper surface and a lower surface and an overall dimension which islarger than the size of the bearing plate. An opening adjacent thecenter allows the tube to pass therethrough. The lower surface isadapted to engage the rock wall while the upper surface of the tandemplate engages the bearing plate. A plurality of tabs on the uppersurface, that are formed by punching and bending parts of the planarsheet from which the tandem plate is made, engage the bearing plateprior to installation forming one unitized assembly. This assembly canthen be installed with the tube being driven into said bore. A pluralityof ribs is formed on the tandem plate for increasing the strengththereof.

Other objects, features, and advantages of the invention will be readilyapparent from the following detailed description of the preferredembodiments thereof taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of illustrating the invention, there is shown in theaccompanying drawings one form which is presently preferred; it beingunderstood that the invention is not intended to be limited to theprecise arrangements and instrumentalities shown.

FIG. 1 is a perspective view of a mine shaft or the like showing aplurality of friction rock stabilizers in combination with bearingplates and tandem plates supporting the roof of the mine;

FIG. 2 is a perspective exploded view showing the combination of atandem plate of the invention with a conventional bearing plate andfriction rock stabilizer, and

FIG. 3 is a perspective view showing the tandem plate of the inventionsecured to a conventional bearing plate and to a friction rockstabilizer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings in detail wherein like reference numeralshave been used throughout the various figures to designate likeelements, there is shown in the figures a tandem plate constructed inaccordance with the principles of the present invention and designatedgenerally as 10.

The tandem plate 10 is intended to be used with a friction rockstabilizer system that includes an elongated metal tube 12 having afirst end 14 that is adapted to be driven into a bore drilled in a rockwall of a mine or the like. The second end 16 of the tube 12 includes aflange 18 formed thereon. The friction rock stabilizer system alsoincludes a bearing plate 20 having a raised conical center portion 22that effectively increases the strength of the bearing plate 20. Theconical center portion rises from a flatter base portion 23. An opening24 adjacent the center of the bearing plate 20 allows the tube 12 topass therethrough but is smaller than the flange 18 so that the flange18 will engage the bearing plate 20.

The friction rock stabilizer system thus far described is, per se, wellknown in the art and, as mentioned above, is commonly referred to as a“Split Set” friction rock stabilizer” available from InternationalRollforms, of Deptford, New Jersey. These systems are also described,for example, in U.S. Pat. No. 6,257,802 to Vosbikian.

Tandem plate 10 of the present invention is intended to be used with thefriction rock stabilizer described above. As will be apparent to thoseskilled in the art, however, the tandem plate 10 could also be used withother similar systems.

The tandem plate 10 is comprised essentially of a planar sheet of metal26 which is, preferably, steel. The sheet of metal 26 includes an uppersurface 28 and a lower surface 30. As can be seen, the overall dimensionof the tandem plate 10 is larger than the size of the bearing plate 20.An opening 32 is formed adjacent the center of the bearing plate and isof a size to allow the tube 12 to pass therethrough. Obviously, theopening 32 is substantially smaller than the overall size of the bearingplate 20.

In order to increase the strength of the tandem plate 10, ribs 34 and 36are formed thereon. These can be formed by stamping and bending thesheet metal from which the tandem plate is made. While two such ribs areshown, it should be readily apparent to those skilled in the art thatany number of ribs can be formed. Furthermore, the ribs can extend indifferent directions.

A pair of spring tabs 38 and 40 is formed in the upper surface 30 of thetandem plate 10. This is preferably accomplished by simply stamping outa portion of the sheet metal 26 from which the tandem plate 10 is madeand then bending the tabs 38 and 40 to the shape shown.

As can be seen most clearly in FIG. 3, the tabs 38 and 40 engage thebase 23 of the bearing plate 20 to hold the same in place. In order toaccomplish this, the tabs 38 and 40 are also comprised of steel and areformed to be at a relatively short distance from the upper surface 30 ofthe tandem plate 10. This allows the tabs 38 and 40 to engage the base23 of the bearing plate 20 to hold the same under tension.

As should be readily apparent to those skilled in the art, when it isdesired to connect the tandem plate 10 to the bearing plate 20, all thatis needed is to slide the base 23 of the bearing plate 20 under the tabs38 and 40. This is done before the two plates are passed over the end 14of the tube 12.

As can be seen from FIG. 1, when the bearing plate 20 and the tandemplate 10 are secured together and the tube 12 is driven into the rockwall 42 of a mine 44 or the like, the lower surface 28 of the tandemplate 10 engages the rock wall 42. As shown, the flexibility of thetandem plate 10 allows the same to conform to some degree to the rockface 42. Any loose material (possibly created during the act of drillingthe hole in the mine roof or wall) will be pinned by the larger tandemplate.

The present invention may be embodied in other specific forms withoutdeparting from the spirit or essential attributes thereof andaccordingly, reference should be made to the appended claims rather thanto the foregoing specification as indicating the scope of the invention.

I claim:
 1. A tandem plate for use with a friction rock stabilizer whichstabilizer includes an elongated metal tube having a first end adaptedto be driven into a bore drilled in a rock wall and a second endincluding a flange thereon, said stabilizer further including a bearingplate having a base with an opening adjacent the center thereof andadapted to fit over said first end of said tube to engage said flange,said tandem plate being comprised of: a substantially planar sheet ofmetal having an upper surface and a lower surface; said tandem platehaving an overall dimension which is larger than the size of saidbearing plate and including an opening adjacent the center thereof of asize allowing said tube to pass therethrough; said lower surface of saidtandem plate being adapted to engage said rock wall, said upper surfaceof said tandem plate being adapted to engage said bearing plate, andmeans carried by said tandem plate for temporarily attaching said tandemplate to said bearing plate while said tube is being driven into saidbore.
 2. The tandem plate as claimed in claim 1 further including aplurality of ribs formed thereon for increasing the strength of saidtandem plate.
 3. The tandem plate as claimed in claim 1 wherein saidmeans for temporarily attaching includes a plurality of tabs carried bysaid upper surface, said tabs being adapted to engage said base of saidbearing plate.
 4. The tandem plate as claimed in claim 3 wherein saidtabs are comprised of metal so as to engage said base and hold the sameunder tension.
 5. The tandem plate as claimed in claim 4 wherein saidtabs are formed by punching and bending them from said planar sheet ofmetal forming said tandem plate, whereby said tabs and said planar sheetmetal are integrally formed together.